Enable continuous delivery with JEP-229 (#62)

https://www.jenkins.io/doc/developer/publishing/releasing-cd/

Author: MarkEWaite

.github/release-drafter.yml

@@ -0,0 +1,54 @@
+# Note: additional setup is required, see https://www.jenkins.io/redirect/continuous-delivery-of-plugins
+#
+# Please find additional hints for individual trigger use case
+# configuration options inline this script below.
+#
+---
+name: cd
+on:
+  workflow_dispatch:
+    inputs:
+      validate_only:
+        required: false
+        type: boolean
+        description: |
+          Run validation with release drafter only
+          → Skip the release job
+        # Note: Change this default to true,
+        #       if the checkbox should be checked by default.
+        default: false
+  # If you don't want any automatic trigger in general, then
+  # the following check_run trigger lines should all be commented.
+  # Note: Consider the use case #2 config for 'validate_only' below
+  #       as an alternative option!
+  check_run:
+    types:
+      - completed
+
+permissions:
+  checks: read
+  contents: write
+
+jobs:
+  maven-cd:
+    uses: jenkins-infra/github-reusable-workflows/.github/workflows/maven-cd.yml@v1
+    with:
+      # Comment / uncomment the validate_only config appropriate to your preference:
+      #
+      # Use case #1 (automatic release):
+      #   - Let any successful Jenkins build trigger another release,
+      #     if there are merged pull requests of interest
+      #   - Perform a validation only run with drafting a release note,
+      #     if manually triggered AND inputs.validate_only has been checked.
+      #
+      validate_only: ${{ inputs.validate_only == true }}
+      #
+      # Alternative use case #2 (no automatic release):
+      #   - Same as use case #1 - but:
+      #     - Let any check_run trigger a validate_only run.
+      #       => enforce the release job to be skipped.
+      #
+      #validate_only: ${{ inputs.validate_only == true || github.event_name == 'check_run' }}
+    secrets:
+      MAVEN_USERNAME: ${{ secrets.MAVEN_USERNAME }}
+      MAVEN_TOKEN: ${{ secrets.MAVEN_TOKEN }}

.github/workflows/cd.yaml

@@ -1,2 +1,3 @@
 -Pconsume-incrementals
 -Pmight-produce-incrementals
+-Dchangelist.format=%d.v%s

.github/workflows/release-drafter.yml

@@ -9,16 +9,15 @@
 
   <artifactId>port-allocator</artifactId>
   <packaging>hpi</packaging>
-  <version>${revision}${changelist}</version>
+  <version>${changelist}</version>
   <name>Jenkins Port Allocator Plug-in</name>
   <url>https://github.com/jenkinsci/port-allocator-plugin</url>
 
   <properties>
-    <revision>1.13</revision>
-    <changelist>-SNAPSHOT</changelist>
+    <changelist>999999-SNAPSHOT</changelist>
     <gitHubRepo>jenkinsci/port-allocator-plugin</gitHubRepo>
     <jenkins.baseline>2.479</jenkins.baseline>
-    <jenkins.version>${jenkins.baseline}.1</jenkins.version>
+    <jenkins.version>${jenkins.baseline}.3</jenkins.version>
   </properties>
 
   <scm>